1. Field of the Invention
The present invention relates to a hinge device for a refrigerator, more particularly, to a hinge device for a refrigerator which can damp in an auto-closing section for closing a door of a refrigerator automatically.
2. Discussion of the Related Art
As well-known to those skilled in the art, a refrigerator is an appliance which keeps various kinds of food fresh such as vegetables, meat, kimchi and the like. The refrigerator repeatedly performs a freezing cycle including compression, condensation, expansion and evaporation to cool an inside thereof, and controls the inside temperature to be optimal based on the kind of the stored food.
Among various kinds of refrigerators, a kimchi refrigerator classified into a draw type, a top cover type and a combination type kimchi refrigerator. The draw type kimchi refrigerator includes a storage space having a front side opened and a door drawable to take out/put the food from/into the storage space. The top cover type kimchi refrigerator includes a storage space having an upper side opened and a door rotating upwardly/downwardly to be opened/closed. The combination type kimchi refrigerator has the draw type and the top cover type combined.
For opening/closing the door of the top cover type and combination type kimchi refrigerator, a hinge device should be provided to connect the door to a body so that the door may be movable upwardly/downwardly. Accordingly, the hinge device has been studied in various methods so far.
Among the hinge devices, hinge devices are disclosed in Korean Laid-Open Patent Publication Nos. 10-2005-0043162, 10-2004-0096425, 10-2004-0073640 and 10-2003-0037377, in which a door can maintain a state of being stopped within a predetermined angle range, in other words, a free stop section: the angle between a storage space and a door is within approximately 85˜20°.
As described briefly, the hinge device includes a rotation shaft, a sliding member and a compression spring. The rotation shaft is mounted within a hinge case defining an exterior of the hinge device to rotate in accordance with rotation of a door. The sliding member is provided within the case to move forwardly/backwardly and the compression spring supplies elasticity to the sliding member.
Thus, the equilibrium between the load of the door, when the door is opened/closed, and the elasticity of the compression spring is balanced so that the door is dropped by its load slowly and not closed suddenly to maintain the state of being stopped within the predetermined range of the angle.
However, the conventional hinge devices having the above configuration has a large moment in an auto-closing section, because the centroid of the door is apart from the hinge shaft in the auto-closing section in which the angle between an upper surface of the storage space and the door is 20˜0°, that is, the section where the door is closely adjacent to the storage space.
Thus, since the moment is larger than the elasticity of the compression spring, there is a problem that the door might be closed by its load suddenly and strongly enough to hurt a user's hand.
To solve the above problem, the hinge devices of Korean Laid-Open Patent Publication Nos. 10-2005-0063170 and 10-2005-0089728 disclose an auxiliary damping unit such as an oil hinge and the like for using air pressure.
However, the above prior art having the above configuration has problems of high production cost as well as low work efficiency, because its structure is too complex. Also, there is another problem that the door is opened heavily when the user tries to open the door fast, because the oil hinge is always operated when he/she opens/closes the door.
Furthermore, there is still another problem that the hinge device has a short usage life, because the load of the door is not uniformly dispersed to the rotation shafts mounted to both opposite sides of the above hinge devices, but concentrated only on either of the two rotation shafts.
Still further, there is still another problem of much noise as well as unsmooth opening of the door, because the prior art hinge devices need much grease to reduce friction of the pair of cams in relative motion and the grease is carbonized by the friction.